In a hybrid vehicle equipped with a generator driven by the engine and a motor for operating the vehicle, for example, the motor is driven by electrical power from a rechargeable secondary battery. Here, the electrical power able to be input to and output from the secondary battery greatly influences the driving performance of the vehicle. If the temperature of the secondary battery falls, the electrical power able to be input to and output from the secondary battery ends up decreasing considerably. Therefore, it has been previously proposed to inhibit decreases in input and output electrical power by raising the temperature of the secondary battery (see, for example, Patent Document 1). In the device described in this Patent Document 1, when the temperature of a secondary battery falls to a prescribed temperature or lower, a secondary battery is charged by driving of a generator by the engine and by regenerative braking while driving, and accordingly, charging and discharging of the secondary battery is repeated to raise the temperature of the secondary battery, thereby inhibiting decreases in input and output electrical power.
However, in the device described in Patent Document 1 described above, regenerative braking while driving and driving of a generator by the engine are always required to charge the secondary battery. In other words, it is necessary to drive the engine in order to raise the temperature of the secondary battery while parked.
Patent Document 1: Japanese Patent Application Laid-open No. 2003-272712